Adjustable contact assembly for resonant reed relays



Oct. 25, 1966 c, BLAKE ET AL 3,281,732

ADJUSTABLE CONTACT ASSEMBLY FOR RESONANT REED RELAYS Filed May 5, 1965 2Sheets$heet 1 "2.! H s; \5 2 I N Q INVENTORS C'uRTls E. BLAKE LANCEBowen:

ATTORNEYS Oct. 25, 1966 c, E BLAKE ET AL 3,281,732

ADJUSTABLE CONTACT ASSEMBLY FOR RESONANT REED RELAYS Filed May 5, 1965 2Sheets-Sheet 2 INVENTORS BLAKE LANCE BOWEN was; Fgwwle u EPMMQ ATTORNEYSUnited States Patent M 3,281,732 ADJUSTABLE CUNTACT ASSEMBLY FURRESONANT REED RELAYS Curtis E. Eiake, llenfield, and Lance Bowen,Rochester, N.Y., assignors to Sargent and Greenleaf, incorporated,Rochester. N.Y., a corporation of New York Filed May 5, 1965, Ser. No.453,456 2 Ciaims. (Cl. 335%) The present invention relates in general tofrequency selective resonant reed relays, and more particularly tostationary contact assemblies for resonant reed relays.

Resonant reed relays customarily comprise a tuned vibratile reed ofparamagnetic material clamped at one end and having a selected naturalresonant frequency of vibration determined by the thickness and lengthof cut of the reed. The reed extends through an opening in a permanentmagnet which sets up a constant magnetic field about the reed, andthrough an electromagnetic air core driving coil to which alternatingcurrent signals are applied to vary the total flux field so as toproduce vibration of the reed when the frequency of the applied signalapproximates the natural resonant frequency of the reed. A stationarycontact is disposed to be periodically engaged by the reed or by acontact on the reed when the reed vibrates with maximum amplituderesponsive to an applied signal frequency corresponding to the selectedresonant frequency characteristic of the reed. Such resonant reed relayshave come into wide use in electronic communication equipment such astelemetering, radiotelephony, mobile radio receiver systems, pagingsystems, remote control systems, encoder and decoder networks, dataprocessing and many other applications where it is desirable toselectively close circuits to activate one selected responder device outof a plurality of devices in signal responder systems.

As the drive level to the reed coil is increased past threshold (thatpoint in voltage at which contact closure occurs) the impedance to thereeds excursion is also increased. With sufficient drive level, the reedwill tend to reverse its direction prior to a reverse in direction ofthe current through the coil. As a result, the apparent frequency of thereed increases since the reed tends to travel faster than the drivingsignal. A further result is that, as the frequency of the driving signalis increased past resonance, the tendency of the reed to travel fasterthan the driving signal continues; thus contact closure occurs forseveral cycles above the point in frequency at which the relay wouldnormally pull in. It is, therefore, also possible to pulse the reed witha signal the frequency of which is above the normal pull-in point with aresultant firing of the reed (contact closure) and the reed will remainso fired until the driving signal is removed or greatly reduced.

The sudden application of a driving signal (pulsing) whose frequency andamplitude are such that contact closure shall occur usually results in amomentary misfire of the reed. That is, the reed hitting the contactcauses the contact to deviate greatly from its normal position. If, onthe next cycle at which contact closure should occur, the contact is notin its normal position, no contact closure may occur.

Once the reed is vibrating, however, although it does not misfire, thecontact still tends to deviate greatly from its normal position. Thatis, as the reed approaches the point of maximum deviation from its restposition, it tends to push the contact slightly past that point; thus,at that time, contact closure ceases and does not occur again until thefollowing cycle. As a result, the percentage of a cycle that contactclosure actually occurs (dwell time) is very low. All of theseundesirable characteristics are related directly to the type of contactused.

3,231,?32 Patented Get. 25, 1966 An object of the present invention isthe provision of a novel resonant reed relay construction which greatlyreduces or eliminates apparent changes in reed frequency with high leveldriving signals.

Another object of the present invention is the provision of a novelresonant reed relay construction which eliminates or greatly reducescontinuous firing or triggering the reed as the frequency of the drivingsignal is increased past the normal pull-in limits.

Another object of the present invention is the provision of a novelresonant reed relay construction which minimizes momentary misfiringwhen the reed is pulsed with a signal whose frequency and amplitudecause contact closure.

Another object of the present invention is the provision of a novelresonant reed relay construction wherein the percentage of a cycleduring which contact closure occurs is increased.

Other objects, advantages, and capabilities of the present inventionwill become apparent from the following detail description, taken inconjunction with the accompanying drawings illustrating a preferredembodiment of the invention.

In the drawings:

FIGURE 1 is a side elevation of a resonant reed relay constructed inaccordance with the present invention with the near wall of theenclosure or casing broken away to reveal the interior;

FIGURE 2 is a horizontal transverse section view of the resonant reedrelay taken along the line 2-2 of FIGURE 1;

FIGURE 3 is a vertical section view of the resonant reed relay, takenalong the line 3-3 of FIGURE 2;

FIGURE 4 is an elevation view to enlarged scale taken along the line 44of FIGURE 3;

FIGURE 5 is a vertical section view taken along the line 55 of FIGURE 4;and

FIGURE 6 is an exploded perspective view of the contact assembly.

Referring to the drawings illustrating a preferred embodiment of thepresent invention, the resonant reed relay structure, generallydesignated by the reference.

character It comprises an elongated rectangular shielding enclosure 11of substantially square cross-section having an integrally formedclosure end wall 12 at one end, which shielding enclosure is preferablyformed of drawn copper and serves to minimize the effects of externalfields. Supported within the shielding enclosure is a rigid frame 13,which may be formed of a channel-shaped elongated thin steel member tohouse the operative components of the reed relay, the frame 13 havingchannel sides 14-, 14 as illustrated in FIGURE 2. The frame 13 supportsa base 15, which is a solid rectangular block of material such as brasswhose periphery conforms to the inner dimensions of the frame and issecured to the frame adjacent the upper end thereof as viewed in FIG-URES l and 3. The base 15 is provided with a central cylindrical opening16 concentric with the medial axis of the frame to receive a conformingcylindrical end portion 17 of the metalic vibratory reed member 18 insecured relation within the opening 16. The reed portion 19 of the reedmember 18 is an elongated thin member of rectangular cross-sectionhaving considerably greater width than thickness, and may for example beformed of nickel-chrorne-steel alloy for temperature stability. Thethickness and length of cut of the reed determines the resonantfrequency and the reed responds to variations in the magnetic fieldsurrounding the reed 19 by vibrating to and fro relative to thestationary end adjoining the portion 17. Spaced from the base 15 andsurrounding the reed 19 is an electromagnetic driving coil 20 wound on adialectric spool or coil form 21 having a rectangular central opening 22through which the reed 19 extends. Adjacent the driving coil 20 is apermanent magnet 23 in the form of a solid rectangular block of simpleone piece construction, made for example, of a well known alnicomaterial, which is peripherally secured to the walls of the frame 13 andhas a rectangular central opening 24 aligned with the open ing 22 of thecoil 20 to accommodate the reed 19. The lower end of the frame 13 isclosed by a mounting block 25, which may be made of an insulatingmaterial such as phenolic resin, secured as by cementing to the frame13. The mounting block 25 is apertured to pass desired electricalconductors including the leads 20' for the driving coil 20 to flexibleconductors, such for example, as conductive coil springs 26 to a disc ofinsulating material 27 through which suitable terminal prongs 28 extendforming male plug terminals which may be inserted into correspondingsockets of an electrical plug to make electrical connection with thecircuitry with which the reed relay unit is to be associated. The disc27 is peripherally secure in a cylindrical aperture in a metalic capmember 29 having a constricted portion 30 of rectangular crosssectioncorresponding to the inner configuration of the shield enclosure 11 andhaving a lip portion 31 to butt against the lower edges of the enclosure11.

The upper end of the frame 13 is supported in the shielding enclosure 11by a block or panel of resilient material 33, such as foam rubber, whichis secured to the frame 13 or base 15, as by cement and peripherallyengages the lateral walls of the enclosure 11, coacting with the springs26 to resiliently support the frame in a manner minimizing the effect ofexternal loading.

The reed 19 is designed to make contact with a stationary contact whenthe resonant reed relay is energized. The stationary contact assembly ofthe present invention is indicated by the reference character 35, andcomprises a contact base member 36, which may be a rectangular strip ofelectrically insulative material such as phenolic block, having acountersunk hole 37 near its lower end to receive a conductive mountingscrew and nut 38 and a threaded hole 39 near its upper end to receive acontact adjustment screw 40. A contact support arm 41 formed of a thinrectangular strip of electrically conductive material such as berylliumcopper having a curved upper extremity 42 lapping the upper end of thecontact base member 36 is mounted against the surface of contact basemember 36 facing the reed 19 by mounting screw and nut 38, and isinclined outwardly from the base member 36 at a suitable angle byadjustment screw 41 bearing against the upper portion of the arm 41. Acontact cushion 43 bears against the supporting arm 41 near the upperend thereof, the cushion being formed by a square or rectangular pad ofsoft, flexible electrically insulative material such as neoprene foam.The contact member 44 is a thin strip of electrically conductivematerial such as beryllium copper having a lower portion 45substantially coextensive with the contact base member 36 in the zone ofthe mounting screw and nut 38 which is secured with the lower endportion of the contact support arm 41 flat against the adjacent surfaceof base member 36. The portion of the contact member 44 rising above theportion 45 may be tapered in profile and includes an intermediateportion 46 inclining away from the support arm 41 to a distancecorresponding substantially to the thickness of the pad 43 and an upperportion 47 bent into substantial parallelism with the plane of the freeportion of support arm 41. The contact cushion 43 may be secured in anysuitable manner to the supporting arm 41, or to the upper portion of thecontact member 44, or to both. The contact member 44 may be bifurcatedif desired by providing slot 48 extending from the upper end thereof asillustrated, to increase the flexibility of the upper portion of thecontact member 44, or the slot may be omitted, as desired. The upper endportion of the contact member 44 serves as the stationary contact to beintermittently engaged by the reed 19, and the reed 19 may directlyengage the upper end portion of the contact member 44 or a contactbutton (not shown), formed for example of silver to minimize the effectsof arcing, may be mounted on the reed to make contact with the contactmember 44.

The contact assembly 35 is mounted in any suitable manner on themounting block 25, as by an L-shaped electrically conductive bracket 49apertured in its upright arm to receive and be secured by the mountingscrew and nut 38 to the contact base member 36 in electricalcommunication with contact member 44 and secured by rivets to themounting block 25 and to one of the springs 26 connected to anappropriate one of the terminal prongs 28. An access opening 50 ispreferably provided in the wall 14 of the frame 13 in axial alinementwith the adjustment screw 40 to permit insertion of a screw driver bitfor adjusting screw 40 and the angular position of support arm 41 toestablish the desired spacing of contact member 44 from the reed 19.

It will be appreciated that when an A.C. signal is applied to thedriving coil 20, a varying magnetic field is established about the reed19. When this field is varied at a rate corresponding to the mechanicalresonant frequency of the reed, commonly at some frequency in the range70 to 800 c.p.s. although sometimes as low as 20 c.p.s. or as high as1600 c.p.s., the reed 19 vibrates, gradually increasing its distance ofexcursion until it strikes the upper end portion 47 of the contactmember 44, once each electrical cycle. Due to the particularconstruction of the above-described contact assembly, particularly theresilient cushioning of the contact member 44 by the pad 43, theflexibility of the contact member 44 above the portion clamped againstthe support arm 41 and base 36, and the fine adjustment of position ofthe upper end 47 thereof, the contact member does not deviate from itsnormal position to any significant degree comparable to the contact wireformerly used as the stationary contact, thereby minimizing thecontinuous firing or triggering of the reed by driving signals whosefrequencies are above the normal pull-in limits, and reducing thepossibility of momentary misfire when pulsed with a signal of-properamplitude and frequency or reduction of contact closure time in cyclearising from the significant deviation of the contact from rest positionoccurring in prior wire contacts.

While only one form of the present invention has been particularly shownand described, it will be apparent that various modifications may bemade within the spirit and scope of the invention, and it is desired,therefore, that only such limitations be placed on the invention as areimposed by the prior art and set forth in the appended claims.

What is claimed is:

1. In a resonant reed relay having an elongated vibratory reed ofelectrically conductive magnetic material normally arranged along avertical axis having one end supported in fixed relation in said relayand a free end portion adapted to vibrate in a transverse plane throughsaid axis over a selected range of excursions responsive to variationsin a surround-ing magnetic flux field of selected frequency, anelectromagnetic driving coil for establishing the varying flux field,and a permanent magnet establishing a biasing magnetic field about saidreed; the improvement comprising an adjustable stationary contactassembly coactive with the free end portion of said reed to beperiodically engaged thereby and complete an electrical circuit throughsaid reed and contact assembly comprising a vertically elongatedinsulative base member having a planar mounting surface facing said axissubstantially paralleling said axis disposed substantially perpendicularto said transverse plane, a deformable contact support arm substantiallycoextensive vertically with said base member in overlying relation tosaid base member between said surface and said axis and having upper andlower ends substantial-1y aligned horizontally with upper and lower endsof said base member, said support arm being secured at a fixed point tosaid mounting surface in abutment therewith adjacent the lower ends ofsaid support arm and base member and having an elongated portionextending to the upper end portion thereof along a plane inclined tosaid mounting surface, an elongated flexible electrically conductivecontact member having a lower end portion fixed to said support arm andmounting surface at said fixed point and including an intermediateportion inclined from the region of said fixed point in angular relationto the plane of said support arm toward said reed and an upper free endportion spaced toward the reed from and substantially paralleling theplane of said support arm to be engaged by the vibrating reed when thelatter is undergoing maximum excursions and establish electrical contacttherewith, a resilient pad interposed between and engaging said endportion of said contact member and said support arm to position saidfree end portion relative to said support arm and resist and dampdeflection of said contact member end portion toward said support arm bysaid reed, and adjustment screw means threaded in said base member andengaging said support arm at said spaced position to vary the angularrelation to said mounting surface of said support arm and the endportion of said contact member positioned relative to said support armby said pad.

2. In a resonant reed relay, the contact assembly defined in claim 1,wherein said contact member is formed of thin sheet metal, said contactmember having upwardly convergent lateral edges along the intermediateand upper end portions thereof defining a truncated triangularconfiguration, and said contact member having a slot extending along thelongitudinal center axis thereof from said upper end into saidintermediate portion dividing said upper end portion into a pair oflaterally spaced narrow segments disposed to be engaged by the vibratingreed.

References Cited by the Examiner UNITED STATES PATENTS 1,835,788 12/1931Knopp. 3,029,326 4/1962 Fischer 200- 3,221,120 11/1965 Mooney et al200-91 X BERNARD A. GILHEANY, Primary Examiner.

R. N. ENVALL, JR., Assistant Examiner.

1. IN A RESONANT REED RELAY HAVING AN ELONGATED VIRBRATORY REED OFELECTRICALLY CONDUCTIVE MAGNETIC MATERIAL NORMALLY ARRANGED ALONG AVERTICAL AXIS HAVING ONE END SUPPORTED IN FIXED RELATION IN A TRANSVERSEPLANE THROUGH PORTION ADAPTED TO VIBRATE IN A TRANSVERSE PLANE THROUGHSAID AXIS OVER A SELECTED RANGE OF EXCURSIONS RESPONSIVE TO VARIATIONSIN A SURROUNDING MAGNETIC FLUX FIELD OF SELECTED FREQUENCY, ANELECTROMAGNETIC DRIVING COIL FOR ESTABLISHING THE VARYING FLUX FIELD,AND A PERMANENT MAGNET ESTABLISHING A BIASING MAGNETIC FIELD ABOUT SAIDREED; THE IMPROVEMENT COMPRISING AN ADJUSTABLE STATIONARY CONTACTASSEMBLY COACTIVE WITH THE FREE END PORTION OF SAID REED TO THEPERIODICALLY ENGAGED THEREBY AND COMPLETE AN ELECTRICAL CIRCUIT THROUGHSAID REED AND CONTACT ASSEMBLY COMPRISING A VERTICALLY ELONGATEDINSULATIVE BASE MEMBER HAVING A PLANAR MOUNTING SURFACE FACING SAID AXISSUBSTANTIALLY PARALLELING SAID AXIS DISPOSED SUBSTANTIALLY PERPENDICULARTO SAID TRANSVERSE PLANE, A DEFORMABLE CONTACT SUPPORT ARM SUBSTANTIALLYCOAXTENSIVE VERTICALLY WITH SAID BASE MEMBER IN OVERLYING RELATION TOSAID BASE MEMBER BETWEEN SAID SURFACE AND SAID AXIS AND HAVING UPPER ANDLOWER ENDS SUBSTANTIALLY ALIGNED HORIZONTALLY WITH UPPER AND LOWER ENDSOF SAID BASE MEMBER, SAID SUPPORT ARM BEING SECURED AT A FIXED POINT TOSAID MOUNTING SURFACE IN ABUTMENT THEREWITH ADJACENT THE LOWER ENDS OFSAID SUPPORT ARM AND BASE MEMBER AND HAVING AN ELONGATED PORTIONEXTENDING TO THE UPPER END PORTION THEREOF ALONG A PLANE INCLINED TOSAID MOUNTING SURFACE, AN ELONGATED